Pancreas

Abstract

The pancreas is derived as an outpouching of the primitive foregut endoderm in the region of the duodenum. It has two main embryologic components: (1) a dorsal bud, first identifiable at 4 weeks gestation, that goes on to become the body and tail of the gland and (2) a ventral bud that produces the head of the gland and the extrahepatic biliary system (Fig. 46.1). As these outpouchings grow, the ventral aspect rotates to fuse with the dorsal aspect by about the seventh week of gestation. The ductal system of the pancreas is derived from these two anlages. The embryonic ventral duct arises from the bile duct, drains with it into the duodenum at the major papilla, and fuses with the dorsal duct to drain the body of the gland as the main pancreatic duct of Wirsung. The embryonic dorsal duct persists as a separate structure in its proximal portion (duct of Santorini), draining into the duodenum at the minor papilla on the medial duodenal wall about 1-2 cm cephalad to the major papilla. In 5%-10% of people, the ventral and dorsal ducts fail to fuse, resulting in a condition known as pancreas divisum.1 In this anatomical arrangement, the majority of pancreatic secretions are carried to the duodenum through the duct of Santorini and the minor papilla (Fig. 46.2). © 2008 Springer New York.